Methods for transferring data within networks, such as local area networks (LANs), metropolitan area networks (MANs), and storage area networks (SANs), rely on standard protocols describing how the data is transferred. Typically the data for a specific network is transferred as data-frames having a format defined by the protocol governing the functioning of the network. Two protocols which are used for transferring data at gigabit/s (Gbps) rates are an IEEE 802.3(Z) Ethernet protocol, issued by the Institute of Electrical and Electronics Engineers, Inc., New Jersey, and an FC-PH Fibre Channel protocol, issued by the American National Standards Institute, Washington, D.C. The Ethernet protocol transfers data-frames over a common bus by ensuring that no data collision occurs when the frames are on the bus. The Fibre Channel protocol transfers data-frames via a switching fabric controlled by a management facility. The facility sets up a path through the fabric between source and destination ports, and the data-frames are routed along the path, ensuring there are no collisions.
Stations within a LAN or MAN operating according to the IEEE 802.3(Z) Ethernet protocol are often grouped together to form a virtual LAN (VLAN), the VLAN being a sub-set of all stations comprised in the area network. The grouping is a virtual grouping, which may relatively easily be changed, since there is no change in physical connections of the LAN when a VLAN is formed. VLANs are implemented by tagging data-frames transmitted from stations of the VLAN, according to the IEEE 802.1q tagging standard, also issued by the Institute of Electrical and Electronics Engineers, Inc. A station can belong to more than one VLAN. However, stations which do not belong to the same VLAN cannot directly transfer data between themselves.
Zoning is a method used in a Fibre Channel SAN to provide separation between groups of stations of the SAN, similar to the VLANs of the Ethernet network. In contrast to VLANs, where the grouping of the sub-sets is determined by tagging of frames of stations within the sub-sets, the grouping of stations within a zone is implemented by the Fibre Channel management facility. The FC-PH Fibre Channel protocol supports zoning when a station is attached to the Fibre Channel fabric, or when an attached station performs a request. In either event, the station receives a list of all the stations belonging to at least one of the requesting station zones. Another method of Fibre Channel zoning, not supported by the FCPH standard but known in the art, uses a programmed hardware filtering table comprised in a switch of the Fibre Channel fabric. For each frame arriving at a switch port, the switch forwards the frame only if the table indicates that the source FC address in the frame belongs to a zone that belongs to an output port.
Methods for transferring data between networks operating under different protocols operating at Gbps rates are known in the art. Dell Computer Corporation of Round Rock, Tex., provides a PowerVault Fibre Channel family of products which may be configured to transfer data between a Fibre Channel network and a gigabit Ethernet (GBE) network. Data transfer between the networks requires a suitably-adapted server.
In an article by Sherri Azgomi, which can be found at http://www.csdmag.com/main/1999/11/9911feat3.htm, and which is incorporated herein by reference, the author describes content addressable memories (CAMs) and gives a number of uses of CAMs. In contrast to a random access memory (RAM), wherein an address is supplied and data at that address is read, data is supplied to a CAM and the address where that data resides is read. An illustration of the use of a CAM in a network switch is given, wherein the CAM extracts and processes address information in incoming data packets. In order to switch the packet to a correct outgoing port, the CAM compares the destination address with a table of addresses stored within the CAM. On-chip implementations of CAM in the form of embedded functions are available as high-density programmable logic devices (PLDs), for example, as an Altera 10K100E device, produced by Altera Corporation of San Jose, Calif.
U.S. Pat. No. 6,032,209 to Mros et al., whose disclosure is incorporated herein by reference, describes a hot-swappable high speed point-to-point interface. The interface incorporates circuitry to eliminate electromagnetic interference when the interface is hot-swapped. The interface provides a connection between a high speed transmitter on a transmitter card, and a high speed receiver on another card. Both transmitter and receiver are able to operate at rates of the order of Gbps, and under GBE or Fibre Channel protocols.